Swift kick, and I'm a major dog lover. Self defense is fair and natural. My plan should a dog ever charge me (hasn't happened yet, although a few have challenged me to side-by-side races) has always been to dismount and put the bike between me and the dog. I would prefer not to kick, because that give it a good chance at my rippling pro cyclist calf muscle If Fido wants to take a bite, it will be of my chainring.